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The influence of self-efficacy on recovery of spontaneous arm use in hemiparetic stroke

THE INFLUENCE OF SELF-EFFICACY ON RECOVERY OF SPONTANEOUS
ARM USE IN HEMIPARETIC STROKE
by
Shu-Ya Chen
________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOKINESIOLOGY)
August 2011
Copyright 2011 Shu-Ya Chen

Stroke is the leading cause of long-term disability. From the patients’ perspective, spontaneous arm use is critical for meaningful recovery of upper limb function. Using the paretic arm spontaneously, without thinking about it, requires a substantial amount of practice. Such practice has been shown to be a powerful mediator for experience-induced neuroplasticity in the injured brain. However, natural practice and engagement of the paretic arm in daily life activities is often suboptimal in spite of apparent capability. One promising construct in this complex problem concerns the social-cognitive domain of self-efficacy. Self-efficacy is defined as one’s perceived confidence about the ability to attain a specific level of performance in a given environment. To engage the paretic limb in a particular motor task requires some level of confidence that performance will be successful – in other words, that the goal is achievable. However, the role of self-efficacy in mediating upper limb functional recovery has received only limited attention from the scientific community. ❧ The overall purpose of this dissertation is to determine the influence of self-efficacy on the recovery process of spontaneous arm use in people with hemiparetic stroke. Given that post-stroke arm use is a meaningful outcome within the context of the International Classification of Functioning, Disability, and Health (ICF) model, we first identified the critical predictors of arm recovery through a systematic review in order to have a better appreciation of upper limb stroke rehabilitation techniques (Chapter 2). According to this systematic review, there was a 317% increase in the frequency of articles on predictors of arm recovery over a nearly 30-year period. Early neurophysiologic and motor-behavior measures were the best predictors at follow-up of arm-specific outcomes. However, we found far fewer studies of social-cognitive factors than of neurophysiological or motor-behavior factors in predicting arm recovery after a stroke. Further, there was no outcome measure classified at the ICF participation level. The paucity of valid and reliable instruments to capture the more distal outcomes associated with activities and participation has likely limited the breadth of available evidence in this field. This systematic review suggests an urgent need for investigating social-cognitive factors and developing direct measures of arm use at the ICF participation level. ❧ Before developing a new measure, we examined two commonly used performance-based measures of spontaneous arm use (the Actual Amount of Use Test (AAUT) and the Motor Activity Log (MAL)) with respect to an important psychometric property – the minimal detectable change (MDC) (Chapter 3). The MDC is used to determine the threshold for whether a pre-post change is due to actual change and not measurement noise from a measurement perspective. We used the dataset from the Extremity Constraint-Induced Therapy Evaluation (EXCITE) trial to calculate the MDC values for both the AAUT and the MAL for each subscale: amount of use (AAUTa, MALa) and quality of movement (AAUTq, MALq). According to the MDC, we found that a greater change in the AAUTa (24.2%) was necessary to demonstrate a true change compared to the AAUTq (14.4%), MALa (16.8%), and MALq (15.4%). The greater variability of the AAUTa is likely due to the low resolution of its scoring system. ❧ Another important finding was that significant training-induced spontaneous arm use was observed in the MAL but not in the AAUT when comparing their MDC values. This discrepancy was the case both immediately after the intervention and at 1-year follow-up. This may be influenced by the nature of the instruments. Specifically, the AAUT has scoring systems with low sensitivity. Furthermore, given that the AAUT tasks were designed to be performed primarily bi-manually, this finding suggests that a pattern of more normal bi-manual arm use did not generalize at the later evaluation point. The minimal generalization to bi-manual tasks may be due to peoples’ low confidence in incorporating the affected arm. In performing the bi-manual tasks, people have the option of using the affected arm. Low confidence in using the arm may influence their choice of using the affected arm even though the strength and movement control in that arm may have improved. Taken together, the findings from Chapter 2 and 3 suggest there is a need to investigate the role of perceived confidence (i.e., self-efficacy), an important social-cognitive factor, on spontaneous arm use with a reliable and valid measurement. ❧ Reaching is a fundamental movement component of the upper limb. Difficulty in reaching after stroke influences the use the affected arm. Schweighofer and his team at the University of Southern California developed a laboratory-based objective measure termed the Bilateral Arm Reaching Test (BART) using a reaching choice paradigm and demonstrated its reliability and validity as a real-time performance-based measure of spontaneous arm use. However, the BART cannot be used to measure self-efficacy. Given that self-efficacy is task-specific, the center-out target reaching choice paradigm modified form the BART was used to develop a self-efficacy measure in order to systematically examine the role of self-efficacy on arm selection in people with hemiparetic stroke. The development and validation of the self-efficacy measure is presented in Chapter 4. We then further examined the relationship between self-efficacy and arm selection, a proxy for arm use, in people with hemiparetic stroke in Chapter 5. ❧ In Chapter 4, fifteen participants with hemiparetic stroke and ten non-disabled adults were recruited. All participants were asked to complete the self-efficacy measure. Reaching is a task used to evaluate the participants’ self-efficacy, they needed to consider which target to reach for and which hand to reach with, forming a hand-target combination. Then, participants were asked to compare two hand-target combinations and identify which combination they had higher confidence in reaching, but without actually moving their arm. The self-efficacy ratings for each hand-target combination were computed and used to test the discriminant validity of the self-efficacy measure. We found that controls’ self-efficacy decreased as target distance increased (r=-.657, p<0.001) and as target location (contralateral to the reaching hand) crosses midline (r=-0.545, p<0.001). In addition, the controls’ self-efficacy was lower for reaching with the non-dominant hand when compared to the dominant hand (p<0.001). In the stroke group, we found significant correlations between self-efficacy and target distance (r=-0.603, p<0.001) and self-efficacy and target location effects (r=-0.378, p<0.001). In addition, participants with stroke rated their self-efficacy to be lower when they had to reach with the paretic hand when compared to the non-paretic hand (p<0.001). The results support the validation of the self-efficacy measure for those with hemiparetic stroke. ❧ The same population was recruited to test the relationship of self-efficacy and arm selection after hemiparetic stroke (Chapter 5). All participants completed the self-efficacy measure (Chapter 4) and the arm reaching test. The arm reaching test required people to move their arm quickly and accurately to reach for the targets once the targets appeared. There were two conditions in the arm reaching test: the spontaneous use condition and the forced use condition. The self-efficacy ratings were extracted for each hand (non-dominant hand for the control group and paretic hand for the stroke group). The probability of hand selection was calculated for the non-dominant arm in the control group and the paretic arm in the stroke group. We found that hand-specific self-efficacy was significantly correlated with the probability of paretic hand selection for the stroke group (r=0.767; p<0.001), but not the non-dominant hand for the control group (r=0.055; p=0.88). More importantly, self-efficacy alone explained 84.2% of the variance in hand selection. The strong relationship between hand-specific self-efficacy and paretic hand selection supports the contention that perceived confidence in task-specific motor capability likely plays an important role in determining hand use after hemiparetic stroke. ❧ Given the identification of a strong relationship between self-efficacy and arm selection in the stroke group, we further examined how changes in self-efficacy would influence paretic limb choice in people with hemiparetic stroke (Chapter 6). An additional sample (n=8) was recruited and randomly assigned to two groups: self-efficacy manipulation (SE) group (n=4) and stroke-related information (SI) group (n=4). We tried to increase the self-efficacy of participants in the SE group through the provision of positive social-comparative feedback. The social-comparative feedback was pre-determined based on one’s performance during the forced use condition of the arm reaching test for the paretic arm. The SI group would receive only stroke-related information, which was irrelevant to their motor performance during the practice. After the self-efficacy manipulation, two out of four participants in the SE group use their paretic arm more, though all participants in the SI group used their paretic arm less. We found that the pre-morbid hand dominance may act as confounders to this result. In addition, the effective dosage and proper timing of the self-efficacy manipulation will need further investigations with a larger sample. ❧ Overall, we have developed a task-specific self-efficacy measure for reaching movements and provided preliminary support for its measurement validity. More importantly, we demonstrated that self-efficacy is an important factor in spontaneous arm use for reaching movements in people after hemiparetic stroke although our self-efficacy manipulation trial could not show sufficiently clinical effectiveness. Together, the findings of this dissertation provide important insight into a little-studied social-cognitive construct of stroke rehabilitation, particularly with respect to the more distal end of the ICF continuum that includes activity and participation. This knowledge may help inform intervention strategies to maximize recovery, and, in turn, influence both participation and quality of life for people following stroke.

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THE INFLUENCE OF SELF-EFFICACY ON RECOVERY OF SPONTANEOUS
ARM USE IN HEMIPARETIC STROKE
by
Shu-Ya Chen
________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOKINESIOLOGY)
August 2011
Copyright 2011 Shu-Ya Chen